Telemetric telescope for direct firing arms

ABSTRACT

RESPONDING TO THE RANGE OF THE POINT FOR WHICH THE TELEMETER IS ADJUSTED THROUGH IMAGE COINCIDENCE.   A TELEMETRIC TELESCOPE PROVIDING COINCIDENCE BETWEEN TWO IMAGES ENSURING ON THE ONE HAND THE OBSERVATION OF AN AREA TO BE WATCHED AND ON THE OTHER HAND THE MEASUREMENT OF THE DISTANCES OF TARGETS LYING IN SAID AREA, THE TELESCOPE IS ADAPTED TO GIVE THROUGH A MERE SIGHTING AND WITHOUT ANY FOCUSING THE DISTANCE OF AT LEAST ONE PREDETERMINED POINT OF THE FIELD OF FIRE AND ACCORDING TO A MODIFICATION THE TELESCOPE MAKES THE ARM CARRYING IT ASSUME THE ANGLE OF ELEVATION COR-

D United States Patent 11113533350 [72] lnventors Francois Arene [56]Reference Cited 46 Besslerw UNITED STATES PATENTS Rue 2,401.705 6/1946Mihalyi 356/9 2,632,357 3/1953 Mihalyi 356/8 P 613396 2964991 12/1960Coeytaux etal. 356/9 [22] PM 1967 1 429 981 9/1922 Taylor et al 356/7[45] Patented June 28, 1971 [32] Priority Feb. 9, 1966 PrimaryExaminer-Ronald L. Wibert [33] France Assistant Examiner0rville B. Chewll [31] 49,011 Attorney-Young & Thompson m ABSTRACT: A telemetrictelescope providing coincidence between two images ensuring on the onehand the observation {541 TELESMETRIC TELESCOPE FOR DIRECT FIRING of anarea to be watched and on the other hand the measure- 4 D F ment of thedistances of targets lying in said area; the rawmg telescope is adaptedto give through a mere sighting and [52] U.S.Cl 356/8, Without anyfocusing the distance of at least one predeter- 356/247 mined point ofthe field of fire and according to a modification [5 1] Int. Cl G0lc3/04 the telescope makes the arm carrying it assume the angle of [50]Field of Search 356/7, 8, 9, elevation corresponding to the range of thepoint for which 255 the telemeter is adjusted through image coincidence.

TELEMETRIC TELESCOPE FOR DIRECT FIRING ARMS BACKGROUND OF THE INVENTIONOur invention relates to telemetric telescopes that is to opticalinstruments adapted on the one hand to ensure observation of an area tobe watched and on the other hand to mea sure distances within said area.

Our invention relates ,chiefly to the application of telemetrictelescopes to fire arms provided for direct firing and more particularlyto infantry arms.

Our improved telescope is designed so as to provide through a meresighting and without any focusing the range of at least onepredetermined point of the field of fire and according to a modificationit gives the arm carrying it the angle of elevation corresponding to therange of the point with reference to which the telemeter has beenadjusted through coincidence of images.

PRIOR ART Telemetric telescopes are already known which allow whentaking aim and giving the arm the desired angle of elevation forensuring telemetric coincidence of the two images of a target as seen bythe marksman to obtain the angle of elevation or sight corresponding tothe range of said target.

Such a telemetric telescope forms the object of the French Pat. No.1,117,609 filed on Dec. 29, 1954 in the names of Coettaux, Deramond (oneof the present applicants) and Hugues and entitled Optical layinginstrument for the direct firing of arms.

The invention underlying said patent has'also formed the object oftheUS. Pat. No. 2,964,991 of Dec. 20, 1960.

The telemeter disclosed in said prior patent forms-in the observer's eyetwo images of the field of fire through two optical paths or systems theaxes of which directed towards the field are vertically shifted withreference to each other as already known in the art. The coincidencebetween the images of different targets at different distances isobtained by giving the telemeter rigid with the arm a slopecorresponding to the angle of elevation.

The coincidence between the images is obtained through a distortion ofthe magnification as to sight of a lens in one of the optical paths.Said distortion consists in giving a slope by a given angle to theaiming line directed towards the target along said optical path with aview to obtaining thus an optical coincidence between the two images.Calculation allows matching with a predetermined accuracy the distortionobtained through the slope of the telemeter with reference to the targetaimed at with a modification of the parallaxis between the lines ofsight in the two telemetric paths. This allows thus the images tocoincide in the observers eye while giving the arm rigid with thetelemeter the angle of elevation corresponding to the target aimed at.

Our invention covers modifications of such a type of telemetrictelescope. The optical system is different and it may be given differentshapes one of which provides telemetric coincidence between the imagesfor a single distance of the target in the field of fire while anotherprovides coincidence for a larger number of different distances.

Furthermore, our invention associates an optical system providingobservation within a large field of fire with such a telemetrictelescope.

SUMMARY OF THE INVENTION In principle, the telemetric telescope includestwo vertically shifted optical paths providing each an image of thefield of fire and the sighting axes of the said paths in said fieldconverge through the very structure of the telescope at a predeterminedunvarying distance from the telescope. Furthermore, a third opticalsystem forming the actual observing telescope produces an image which isindependent of those produced through the telemetric paths, the systemconstituted by all said images being observed through a single eyepiece.

In a preferred embodiment, a concave mirror forms the common objectivefor both telemetric paths.

In a more complete modification, the telescope rigid with an arm andserving as a sighting glass for the latter includes in one of thetelemetric paths ahead of the objective-forming mirror a group ofanamorphosing prisms the magnification of which varies with the sight inaccordance with a law defined by a conventional optical calculationwhich causes the deflection of the aiming axis in the telemetric trackconsidered and which defines the range of the location to be observed inthe field of fire to correspond to the angle of elevation equal to saidsight of the fire arm rigid with the telescope.

Preferably, the achromatic group of anamorphosing prisms operating inthe vicinity of the minimum deflection is constituted by three prismscut out of a common block of glass having acute optical angles andarranged symmetrically with reference to a plane, the first prism lyingto either side of said plane of symmetry while the other prisms theapical angles-of which are smaller than that of the first prism arespaced with reference to the latter in head to tail relationship withsaid first prism.

DRAWINGS Our invention will be better understood from inspection of theaccompanying drawings illustrating an embodiment of said invention:

FIG. 1 shows the compound image formed by the telemetric telescope asseen by the observer.

FIG. 2 is a perspective diagram of an embodiment of our improvedtelemetric telescope.

FIG. 3 is a perspective view of a multiple prism incorporated with thediagram according to FIG. 2.

FIG. 4 is a vertical sectional view of a group of anamorphosing prismsincorporated with the diagram illustrated in FIG. 2 according to amodification of our improved telemetric telescope.

EXAMPLES OF THE INVENTION The telemetric telescope illustrated in FIG. 2includes a first telemetric path A defined by the path of an axialluminous ray, a second telemetric path B and the actual observationtelescope C, which latter are also defined by the path of thecorresponding axial luminous rays.

The upper telemetric path A includes a front lens [0 beyond which theluminous rays are reflected by the total reflection prisms l1 and 12spaced by a distance T equal to the telemet ric base as well known inthe art. It is important that the reflecting surfaces of said prisms mayform with each other a constant angle approximating 0 whatever may bethe shocks and differences in temperature to which the telescope issubmitted; this result is achieved for instance by gluing the prisms l1and 12 on a silica support of an unvarying shape. The constancy of saidangle may also be obtained by replacing both prisms by pentagonal prismsaccording to a further conventional solution.

Beyond the prism 12 at the input of which is located the pupil ordiaphragm forming the input 32 of the upper telemetric path A, thelatter reaches the objective-forming mirror I3. The latter is common toboth the upper path A and the lower path B of the telemeter which tracksare still separate, although their axes lie in a common horizontal planeahead of the objective 13. The horizontal diameter of the mirror 13 isfor this reason equal to twice the span of the beams following thetelemetric paths and its optical axis is shifted with reference to themedial rays of the two beams by about one quarter of the openingcorresponding to its horizontal diameter. In the case illustratedalthough this cannot be considered as a limitation, the objective 13forms a catadioptric system. Generally speaking, such a system has thedrawback of leading to the closing off of the central part of the pupil.Now, this drawback does not appear in practice in the present case byreason of the small telemetric field inherent to our invention since aswill be shown the same eyepiece collects preferably both the veryreduced field of a telemeter providing a large magnification and thelarge field with a low magnification of the actual telescope. Incontradistinction, the catadioptric ob jective shows numerous advantagessuch as a better correction of spherical aberrations and of chromatismthan in the case of a dioptric objective for a predetermined opening anda predetermined focal length and the reflection of the beam leads to asmaller bulk for the apparatus without this requiring the incorporationof any further reflecting parts.

After reflection on said catadioptric objective 13, the upper telemetricpath reaches the focal plane of said objective which is caused to lie inthe vicinity of the prism 12.

In said focal plane, the path is shifted by means of a total reflectionprism 14 which is positioned so that the focal plane of the objective 13may be preferably but not of necessity located along the output surfaceof said prism 14.

Considering now the lower telemetric path B, it begins with the frontlens 15, passes through the input diaphragm 16 located approximately intransverse registry with the prism 12, after which it impinges on thehalf of the catadioptric objective 13 serving for said track B, whichfinally reaches the focal plane of said objective 13 lying on the outputsurface of the total reflection prism 14.

Thus, the two field images obtained by the two telemetric paths A and Bare superposed on the output surface of the prism 14. To allow seeingthrough the eyepiece only one of the two images in the correspondingsections 1 and 2 of the telemetric field illustrated in FIG. 1,prismatic blades 17 illus trated in FIG. 3 are located in the planecommon to the two images formed on the output surface of the prism 14,said blades producinga slight deflection of the medial rays in bothpaths, so that the pupils in the telescopic tracks A and B may registerafter they have passed through said blades.

' Beyond said prismatic blades 17, both telemetric tracks pass through acommon centered system comprising prisms and two groups oflenses; adiaphragm 20 is inserted at the location corresponding to anintermediate plane common to both telemetric tracks, so as to cut outcompletely any parasitic rays as well known in the art.

Said arrangement is designed so as to produce two erect images of thelandscape or field of fire, which images are distributed between thesections 1 and 2 of the telemetric field (FIG. 1) corresponding to thetwo telemetric tracks A and B and are located on the output surface ofthe total reflection prism 21. Said latter surface corresponds to theupper section of the object field of the eyepiece 22 common to thetelescope and t the telemeter and lies in principle substantially in itsobject focal plane.

The micrometric lines 4,7,8 are engraved on the output surface of theprism 21 at suitable locations in the section 2 of the telemetric fieldas shown in FIG. 1.

The sighting telescope associated with the above-described telemeterincludes the above-referred to eyepiece 22 and an image-erectingobjective system including the objective 23 and the erecting prism 24which may obviously be of a type different from that illustrated in FIG.2. Said image-erecting system provides an image of the landscape on therear surface of the glass blade 25 which surface forms a lower extensionof the output surface of the prism 21 and carries an engravedmicrometric scale as illustrated in FIG. 1. Said output surfaceregisters with the focusing plane of the eyepiece 22, in principle itsfocal object plane.

The positioning and centering of the output planes of the sightingtelescope and of the telemeter are ensured for instance by deflectingprisms located in the focal plane of the eyepiece.

The upper section of the focal object plane of the eyepiececorresponding to the output surface of the prism 21 shows the telemetricfields 1 and 2 and underneath same on the output surface of the blade 25there lies the field 3 of the actual telescope. It is thus possible toobtain the general appearance of the field illustrated in FIG. 1.

In said field, the lower telescopic section 3 provided with a smallmagnification and a large field corresponds to the actual observing orsighting telescope, while the upper section corresponds to the largemagnification reduced field telemeter. One of the telemetric paths Aproduces an image on the area ll while the other telemetric path B formsits image on the area 2 lying to either side of the area 1 correspondingto the path A. Coincidence is to be obtained between the section 38B ofthe image of the target formed on the area 1 and the remainder of theimage 38A of said target formed on the area 2.

In a first type of telemetric telescope, the telemetric coincidence isensured structurally for a predetermined distance d which may be termedthe fighting distance by causing the axes A and B of the object space toslope with reference to each other by a predetermined angle a equal tothe parallactic angle through which the telemeter base that is thedistance separating the centers of the input glasses 10 and 15 as seenat the distance to be considered. The two images of the object in thefield of fire located at said fighting distance are seen as incoincidence.

This is the case for instance of the horizontal lines of the landscapelocated at a fighting distance.

In the simplest embodiment of our invention illustrated in FIG. 1 areference mark constituted by a horizontal line 4 in the telemetricfield corresponds to another reference mark forming the apex of theangle 5 in the observation field or field of fire. These reference marksare such that when the target lies at fighting distance, the two lowerlines of the images 37 and SBA-38B of the target register respectivelywith the reference marks 5 and 4.

It is also possible in such very simple telemetric telescopes to includea reference mark 7 adjacent the reference mark 4. Said reference mark 7is positioned in a manner such that the angular spacing of the objectspace corresponding to the spacing of said two reference marks 4 and 7in the image plane may be equal to the difference in parallaxis of thebase seen from the distances d and d. Thus, if a horizontal line of theimage of the target registers in the field 2 with the reference mark 4and in the field l with the reference mark 7, the range of said targetwill be exactly equal to d.

The apparatus described may also carry corresponding spaced referencemarks 8 and 9,8 and 9', etc....as illustrated in FIG. 1. Each of thecouples 89 or 89 corresponds to same points of the object in the fields2 and 3 under a succession of ballistic angles of sight of the armcorresponding to different ranges higher than d. Said lines 478,8etc....on the one hand and 5,9,9 on the other hand may form a scale ofranges.

Obviously, the telemetric diaphragms may be simplified and include onlya separating line in which case each telemetric path leads to thecorresponding half, the left-hand or the righthand half of the fielddefined by the diaphragm.

An improvement in the telemetric telescopes described hereinaboveconsists in providing coincidence between the images of straighthorizontal lines of the object space in the sections 1 and 2 of thetelemetric field exactly in registry with the sighting lines4,8,...corresponding to distances d d,...of said horizontal lines fromthe telemeter.

Said improvement consists in introducing a prismatic system providing ananamorphosis of the landscape in a vertical direction. Such an opticalanamorphoser may be located in either of the telemetric tracks A or Bahead of the input pupil.

FIG. 4 relates to the case where the anamorphising system 26 is insertedbetween the prisms 11 and 12 at a point where the telemetric path A hasnot yet met any convergent optical element. The selected anamorphoserconstituted solely by prisms is an afocal system and it has to opticallysatisfy the conditions referred to in the preceding paragraph and tothis end it produces through its introduction in one of the telemetricpaths a modification in the magnification which becomes a function ofthe sight in a manner equivalent to a variable inclination for eachsight with reference to the object axis in the track B. The anamorphoseris designed and positioned in a manner such that when following forinstance the luminous rays starting from the ends of the lines 4,8 ofthe section 2 of the telemetric field in a direction opposed to theprogression of the light along each of the paths A and B, there isobtained a convergence of the luminous rays at object points locatedahead of the telemeter respectively at distances (1,. and dcorresponding to the ranges defined by the lines 4 and 8. Theconvergence of said luminous rays in the object space at predeterminedpoints of said object space is measured by the parallactic angle underwhich said points seek the vertical base of the telemeter. in practice,the unvarying character of the telemeter should be such that said anglemay be measured with an accuracy of a magnitude of a sexagesimal second.Of course, when following a luminous ray in a direction opposed to theprogression of light starting from the line 9 of the telescopemicrometer, which line corresponds to the line 8 of the telemetermicrometer, there is obtained beyond the image erecting prism 24 and itsobjective 23 a luminous ray passing in the vicinity of the point aimedat the distance d, within the accuracy of the desired aiming. that is ofa magnitude ofa few sexagesimal minutes. Thus, the association of thetelemeter with the telescope need not be executed mechanically ascarefully as the association between the two telemetric paths A and B.

The telemetric method which allows aiming directly a gun by giving it asighting angle corresponding to the telemetrically measured distanceafter a preliminary adjustment of the axes has already formed the objectas mentioned hereinabove of the prior French Pat. No. 1,1 17,609 with adifferent optical system.

However, in accordance with our present invention the selectedanamorphising system is constituted in an original manner by threeprisms 27,28 and 29 characterized by the corresponding apical anglesC,D,Ev The ridges of said prisms are perpendicular to the vertical planecontaining the base of the telemeter in a manner such that they mayproduce a cylindrical anamorphosis extending in a vertical direction.The preferred data for said anamorphiser are as follows:

the bisecting plane of the angle D of the intermediate prism 28 forms aplane ofsymmetry for the anamorphiser C=E which is a result of thepreceding condition the ridges C and E are located on the side of theoptical path opposed to the ridge D; in other words, the prisms 27 and29 are set in head to tail relationship with reference to the prism 28the empty angular space F between the prisms 27 and 28 and the emptyangular space G between the prisms 27 and 29 are equal.

the three prisms 27,28 and 29 are cut out of a single block of opticalglass.

a luminous ray passing through the prism 28 perpendicularly to the planebisecting the angle D follows a path corresponding to a minimumdeflection in the prismatic system considered as a whole.

The empty angular spaces F and G are selected after D and C=E have beendefined, in a manner such that the whole system is substantiallyachromatic for the'luminous path corresponding to a minimum deflection.

This leads to the possibility of an infinite series of anamorphoserssatisfying the preceding conditions for predetermined values ofD andofC=E.

The anamorphoser to be chosen is that which is capable of producingunder the best conditions an anamorphosis such that when following adirection opposed to the progression of the luminous rays, a bundle ofplanes adapted to be superposed over the bundle of the planesP4,P5,P8,...passing through the optical center of the objective l3 andthe horizontal lines 4,8,...defining the sights in its focal plane maybe transformed into a bundle of planes P'4,P'8,...which is closer whileany two planes P4,P8 for instance form with each other an angle P4, P'8equal to the angle P4,P8 ininus the difference between the parallacticangles under which the verti- LII cal base of the telemeter is seen fromthe points 0c, Oi of the object space corresponding to the sightsdefined by said lines 4 and 8.

The anamorphoser being thus selected, its angular setting is adjustedwith reference to an axis parallel with the ridges of the prisms so thatsaid setting with reference to the bundle of planes P4,P8 produces theprecedingly defined anamorphosis. Said angular setting is always verynear that which causes the luminous rays following the telemetric pathto pass in the vicinity of the path corresponding to a minimumdeflection.

Finally, the prism 11 is rocked by a small amount so as to producethrough a general shifting of the planes in the direction opposed to thedirection of the light, the suitable convergence of the luminous rayswhich have passed along the two telemetric paths through object pointsOc,Oi as disclosed hereinabove.

The advantages of said prismatic anamorphoser are as follows:

it allows comparatively large modifications in the anamorphosingmagnification as provided by the large angles of incidence of theluminous rays while said magnification remains approximately equal to lfor minimum deflection conditions the possibility of obtaining saidmodifications in the anamorphotic magnification associated with thepossibility of interpolating numerous solutions depending on the initialselection of the two parameters D and C=E lead to an anamorphotic lawwhich matches suitably the law defining the angles of elevation of thearm as functions of range within the scale of ranges selected saybetween 200 and 600 meters the possibility of keeping a magnificationapproximating unity allows providing for the two telemetric tracksjuxtaposed objectives of same focal length or even a commonobjective-forming mirror, as disclosed, which ensures the unvaryingadjustment ofthe telemetric structure defining materially the telemetricbase lastly, there is obtained through the inverted arrangement of theprisms having the same index of refraction a substantially completecorrection of the apparent primary and secondary chromatism which wouldotherwise act detrimentally on the accuracy of the telemeter.

It is apparent that the optical system associated with the arm allows:

watching the firing field in front of the arm for which an opticalsystem with a large field is required an estimation of distance with asuitable accuracy i.e. with a sufficient telemetric power a laying withone or more reference marks carried by the spider lines of the telescopefor predetermined ballistic angles of sight.

It is of advantage to provide an apparatus with a sufficiently smallbulk for it to be permanently secured on the fire arm without it beingnecessary to fold or dismantle the telemetric structure.

It is also of advantage to execute in a substantially simultaneousmanner the telemeter and laying operations:

either in the case of a grazing fire executed with an unvarying sight orfighting sight for which the marksman must make sure that the distanceof the target is not greater than the maximum distance defined byregulation or else, in the more general case, of a direct firingexecuted with a varying sight according to opportunity taking intoaccount the distance at which the target is estimated.

The optical systems known hitherto and associated with infantry armsused for direct firing do not provide such combined possibilities.

In contradistinction, our improved type of apparatus is designed so asto allow:

watching the field of fire of the arm the simultaneous execution oftelemetric and aiming operations in particular when firing with afighting sight the permanent transportation of the apparatus on the armwithout any folding or dismantling of the telemetric structure. Thestarting points of the invention are as follows: it is sufficient toprovide a very broad field with a moderate magnification for it to bepossible to watch the field of-fire for telemetric purposes, a narrowfield is sufficient if the aiming has been first made in a rough mannerwith the ac tual telescope the small bulk requires a short telemetricbase and consequently a large magnification for the telemeter in orderto obtain a sufficient telemetric power.

Three types of apparatus have thus been designed starting from suchprinciples:

firstly a simplified apparatus adapted to produce a single telemetricresult and characterized by a harmonious association of two telemetrictracks for a single range, in principle the maximum range d of firingwith a fighting sight, which range is associated in the telescope with aballistic sighting reference mark which may be a single mark or a mainmark secondly an apparatus directly derived from the preceding one andadapted to provide two telemetric results, in which apparatus thetelemetric tracks are harmonized for a single first range, in principlethe maximum range 11,. of firing with a fighting sight, while it allowsfurthermore comparing the difference in parallaxis between the images ofthe target seen through the two telemetric paths, with the parallacticspacing corresponding to a second range d slightly greater in principlethan d thirdly, a more intricate apparatus providing a multiplicity oftelemetric data and ensuring, in proximity with each of a number ofsighting reference marks, a correspondence between the telemetric dataand the ballistic sighting angle, which result is obtained with thesystem of prisms referred to hereinabove.

For the execution of an arm incorporating optical apparatus of any ofthe three above-disclosed types, the marksman should:

observe the target or the point of passage to be watched on the area 3of the eyepiece provide a rough aiming by resorting to the referencemark finish the aiming by resorting to the reference mark 4 whileexamining the coincidence between the horizontal lines in the vicinityof last-mentioned reference mark in the fields it and 2, said telemetricobservation being executed without any substantial further delay.

When the comparison between the horizontal lines is satisfactory themarksman may fire immediately by making the reference mark 4 forinstance corresponding to a fighting sight register either with thelower part of the target or with its center. Otherwise, the marksmanattempts firing by resorting to one of the reference marks 8corresponding to the range he has to estimate.

More particularly, in the case of apparatus of the third type referredto, the marksman resort to the reference mark 8 in the vicinity of whichcoincidence is obtained between the horizontal lines in the twotelemetric areas 1 and 2. When said telemetric operation has beenexecuted the marksman can:

when firing on a target, he may aim at it by resorting to the referencemark 8, said aiming operation being performed almost without any furtherdelay or else, if it is desired to watch a point of compulsory passage,he notes the reference line 9 corresponding to the abovementionedreference mark 8.

We claim:

1. A telemetric telescope comprising means defining two optical pathsincluding an objective common to said two paths and an eyepiece commonto said two paths with the lines of sight of the two paths verticallyspaced apart and converging and crossing each other a predetermineddistance forwardly of the telescope, means to dispose the images alongsaid two paths viewed through said common eyepiece in register with eachother vertically at said predetermined distance and vertically displacedfrom each other at distances other than said predetermined distance, afurther objective so disposed as to form a further image of the sightedobject in the focal plane of said common eyepiece, the image formed bysaid further objective being substantially smaller than the imagesformed by said first-mentioned objective, at least two fixed referencemarks, and means for forming in said focal plane of the eyepiece imagesof said fixed reference marks one of which occupies the same positionrelative to one of the images along said two paths as does the otherreference mark image relative to said further image,

2. A telemetric telescope as claimed in claim 1, in which said commonobjective is a concave mirror whose surface is intersected by said pathsat laterally spaced locations.

